which two of the following classes exist in Magento

Which two of the following classes exist in Magento?
a. Catalog_Model_Product_Type_Composite
b. Catalog_Model_Product_Type_Virtual
c. Catalog_Model_Product_Type_Price
d. Catalog_Model_Product_Type_Physical
e. Catalog_Model_Product_Type_Index
Correct answer is :

b. Catalog_Model_Product_Type_Virtual
c. Catalog_Model_Product_Type_Price